1. Field of the Invention
This invention is directed to methods for draping a surgical incision site prior to surgery. Specifically, the methods of this invention involve the in situ formation of a polymeric drape over a mammalian skin surface at the surgical incision site. An incision is made through the drape and surgery is then conducted through the incision.
2. References
The following publications, patent applications and patents are cited in this application as superscript numbers:
.sup.1 Masterson, M. D., "Skin Preparation", Chapter 9, in Surgical Infections, Diagnosis and Treatment, Meakins, Ed., Scientific American, Inc., New York, USA, Publisher, pp. 119-125 (1994) PA0 .sup.2 Osuna, et al., "Comparison of an Antimicrobial Adhesive Drape and Povidone-Iodine Preoperative Skin Preparation in Dogs", Veterinary Surgery, 21(6):458-462 (1992) PA0 .sup.3 Hagen, et al., "A Comparison of Two Skin Preps Used in Cardiac Surgical Procedures", AORN Journal, 62(3):393-402 (1995) PA0 .sup.4 Alexander, et al., "Development of a Safe and Effective One-Minute Preoperative Skin Preparation", Arch. Surg., 120:1357-1361 (1985) PA0 .sup.5 Chiu, et al., "Plastic Adhesive Drapes and Wound Infection After Hip Fracture Surgery", Aust. N.Z. J. Surg., 63:798-801 (1993) PA0 .sup.6 Barley, U.S. Pat. No. 5,306,490, Methods for Retarding Blister Formation by Use of Cyanoacrylate Adhesives, issued Apr. 26, 1994. PA0 .sup.7 Barley, et al., U.S. Pat. No. 5,254,132, Methods for Treating Suturable Wounds by Use of Sutures and Cyanoacrylate Adhesives, issued Oct. 19, 1993 PA0 .sup.8 McIntire, et al., U.S. Pat. No. 3,654,239, Process for the Preparation of Poly(.alpha.-Cyanoacrylates), issued Apr. 4, 1972 PA0 .sup.9 Barley, et al., International Patent Application Publication No. WO 93/25196, Methods for Treating Non-Suturable Wounds by Use of Cyanoacrylate Adhesives, published Dec. 23, 1993 PA0 .sup.10 Barley, et al., U.S. Pat. No. 5,653,789, Methods for Reducing Skin Irritation From Artificial Devices by Use of Cyanoacrylate Adhesives, issued Aug. 5, 1997 PA0 .sup.11 Tighe, et al., U.S. Pat. No. 5,403,591, Methods for Inhibiting Skin Ulceration by Use of Cyanoacrylate Adhesives, issued Apr. 4, 1995 PA0 .sup.12 Tighe, et al., U.S. Pat. No. 5,580,565, Use of Cyanoacrylates for Providing a Protective Barrier, issued Dec. 3, 1996. PA0 .sup.13 Ritter, et al., "Retrospective Evaluation of an Iodophor-Incorporated Antimicrobial Plastic Adhesive Wound Drape", Clinical Orthopedics and Related Research, pp. 307-308 (1988) PA0 .sup.14 Duhaime, et al., "Distribution of Bacteria in the Operating Room Environment and its Relation to Ventricular Shunt Infections: a Prospective Study", Child's Verv. Syst., 7:211-214 (1991) PA0 .sup.15 Modern Plastics Encyclopedia (1997)
All of the above publications, patent applications and patents are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent application or patent was specifically and individually indicated to be incorporated by reference in its entirety.
3. State of the Art
Reducing morbidity and/or infection associated with surgical procedures necessitates the thorough preparation of the patient's skin prior to initiating any incision into the skin as part of the surgical procedure. The primary reason for patient skin preparation is to reduce the risk of wound infection by introduction of microbes into the incision site.sup.1 from either skin microbes or from air borne microbes..sup.14 In turn, reduction in such risk correlates, obviously, with reductions in the population of microbes on the skin surface and especially at the skin surface adjacent to the incision site.
Suitable skin preparation involves, for example, application of an antimicrobial agent onto and around the skin surface adjacent to the incision site which reduces the population of microbes on these surfaces and, hence the relative risk of infection. However, the skin is never completely sterilized during these procedures and microbes from hair follicles and sweat/sebaceous glands will migrate to the surface of the skin thereby raising microbial populations and accordingly relative infection risks..sup.2 To counter possible microbial migration into the incision, it has become common practice to employ a surgical incise drape over the patient's incision site.
Conventional surgical incise drapes include those which comprise preformed, sized polymeric films coated with a pressure-sensitive adhesive. In some cases, an antimicrobial agent is incorporated directly into the adhesive in order to permit a continuous release of the antimicrobial agent onto the skin..sup.3,13 After application of an antimicrobial agent onto the skin surface of the patient, the surgical incise drape is applied, adhesive side down, with pressure to effect adherence of the drape to the skin. A surgical incision is then made through the drape and the requisite surgery is conducted through this incision. After completion of the surgery, the drape is conventionally removed from the skin surface prior to final incision closure.
Notwithstanding the benefits associated with a surgical incise drape, several problems exist which have both limited the general applicability of these drapes to all surgical incisions and have actually increased the relative risk of infection. Specifically, the first most common and potentially serious problem associated with the use of conventional surgical incise drapes is the separation or lifting of the drape from the skin surface during surgery. In one study, it was reported that up to 44% of the drapes experienced at least partial separation during human surgery.sup.2. In turn, Alexander, et al..sup.4 report a six-fold increase in infection rates in operations in which the surgical incise drape separated from the skin during surgery as compared to infection rates in which the drape did not separate from the skin. Without being limited by any theory, it is generally believed that occlusion of the skin by the surgical incise drape provides a moist, warm skin surface which encourages microbial growth. It is further believed that separation of the drape from the skin during surgery permits migration of microbes and/or microbial growth at these sites and, accordingly, in such cases, the use of a drape actually promotes rather than retards microbial populations at the incision site.
Non-adherence of the surgical incise drape to the patient's skin is, of course, related to adhesive failure as well as wrinkling of the preformed polymeric film during application. In the former case, this has lead to some attempts to increase the amount and/or strength of adhesive employed in the drape to secure the drape to the mammalian skin surface. However, this in turn may lead to more rather than fewer complications. In particular, since the drape is conventionally removed from the skin shortly after surgery by, e.g., the peeling or pulling off of the drape, an increase in the relative strength of the adhesive leads to increased difficulty in removing the drape from the skin. The effort required to effect removal can also lead to skin tearing and irritation, especially adjacent to the incision site, as well as removal of hair. Skin tearing is clearly disadvantageous and invariably raises additional infection risks because the mammalian skin surface is open (compromised) and therefore susceptible to infection. Moreover, the removal of hair (shaving) has also been associated with increased infection rates.sup.2 and hair removal due to adhesive/drape removal from the mammalian skin can also be expected to provide similar increased infection rates.
In the latter case, wrinkling of the polymeric drape is essentially irreversible because the wrinkles cannot be smoothed out absent complete removal of the drape and drapes, once removed, typically cannot be reapplied to the skin. Additionally, air pockets found in the wrinkles of such drapes are undesirable because they provide a source of microbes adjacent to the skin and, in some cases, promote microbial growth. Wrinkling of the polymeric film is common to most applications of the surgical incise drapes but is particularly problematic with contoured surfaces such as elbows, knees, bony hips, etc. This, in turn, has limited the use of such conventional drapes.
An additional problem associated with preformed polymeric films used as surgical incision drapes arises because such drapes do not conform well to three dimensional contours of the human body thereby increasing the likelihood of separation during surgery. For example, while abdominal areas through which the surgical incision is to be made are typically good candidates for conventional surgical incise drapes, other surfaces such as elbow, knee, foot, and bony hip surfaces (as examples) have three dimensional contours which render consistent adherence of the drape over the incision site during surgery problematic at best. In this regard, Chiu, et al..sup.5 report that the use of sterile adhesive drapes during hip fracture surgeries appeared to have actually encouraged microbial accumulation in the skin adjacent to the wound.
Still a further problem arises from the fact that many adhesives employed with preformed polymeric films do not adhere well to hair thereby limiting their utility.sup.2. Additionally, as noted above, shaving to remove hair prior to surgery has been clinically associated with increased wound infection rates.
In an alternative embodiment, the art has proposed formation of surgical incise drapes by the use of emulsions/solutions containing a volatile organic solvent and a polymer. Upon application to the skin, the solvent dissipates leaving a polymeric film which acts as the incise drape. Significant problems exist with such a procedure and, in particular, the polymeric film lacks strong adhesion to the skin and the volatile solvent can create irritation (e.g., skin, nose, etc.) as well as can be the source of a fire hazard in the operating room.
Lastly, while the most important purpose of using surgical incise drapes is to prevent postoperative wound infections, the simple fact of the matter is that the drapes of the prior art are removed shortly after surgery and there is, accordingly, no postoperative antimicrobial effect available to the skin surface at the surgical incision site.
This invention is directed, in part, to the discovery that the in situ formation of a biocompatible polymeric drape at the surgical incision site prior to surgery by application of a biocompatible prepolymer composition overcomes many of the prior art problems associated with the use of conventional surgical incise drapes and additionally provides incremental advantages heretofore not achieved by conventional drapes. For example, certain of the prepolymers described have bacteriostatic properties and, in any event, the prepolymers permit the inclusion of compatible antimicrobial agents if such is desired. Still another advantage is the formation of an appropriately configured drape without the need to modify the dimensions provided with commercial preformed polymeric drapes. Still further, the methods of this invention result in incise drapes which mold directly to the multiple contours of the intended surgical site.
The use of biocompatible prepolymers per this invention is in contrast to known uses of prepolymers, such as cyanoacrylates, as alternatives or adjuncts to sutures.sup.7 or as hemostatic agents.sup.8. Other described uses of cyanoacrylate prepolymers include their use in preventing friction blister formation.sup.6, treating small non-suturable wounds.sup.9, and in inhibiting surface skin irritation arising from friction between the skin surface and artificial devices such as tapes, prosthetic devices, casts, and the like..sup.10 Still further cyanoacrylate prepolymers have been used to inhibit formation of decubitus ulcers.sup.11 and in the prevention of skin irritation due to incontinence..sup.12